There are many situations when it is either not desired or not legal to utilize certain types of wireless communications. One good example is in the corrections environment, where the correctional institution forbids wireless communication by inmates because such communications are difficult or impossible to monitor and/or control. Law enforcement entities monitor telephone conversations conducted by inmates within correctional facilities for various reasons. The telecommunications equipment available for use by detainees within the corrections environment meet various requirements of governments and police by monitoring and/or recording telephone conversations as needed.
Cellular technology has progressed in form and size to a point that inmates in the corrections environment find ways to hide and smuggle cellular phones into corrections facilities. These phones are then used by inmates to circumvent the required monitoring and/or recording and are often used to communicate amongst themselves to coordinate unauthorized or dangerous activities within the corrections facility.
In correctional facilities, inmates are limited to a small number of individuals that they are permitted to call by way of an approval process. These often include family members, lawyers, and friends. All such calls take place in a very controlled environment, facilitating monitoring and recording, as necessary and legal. Normally, inmates are not permitted to make calls to certain individuals such as judges, jury members, witnesses, known accomplices, etc., to prevent harassing or other unwanted calls. Some correctional facilities also restrict the time of day and length of calls. Such monitoring is typically computer controlled at the correctional facility and/or at remote locations, at times, includes human monitoring and/or control. Additionally, certain laws and privacy norms prohibit recording of certain conversations such as conversations between an inmate and his/her attorney.
The penetration of, for example, cellular phones into many correctional facilities has become alarming. Imagine the harm that results in a purported killer having a smuggled cellular phone and calling judges and jury members every night with threats if he is convicted; or being able to continue with unlawful activity through the use of a cellular phone. Yet, cellular phones still find their way into such institutions and are well hidden. To avoid detection and to extend battery life, often the cellular phones are powered completely off when not in use, thereby not emitting any type of radio frequency signal until the inmate desires to make a call. Such devices are so small that they are easily hidden and, because there is no radio frequency emissions when powered off, such devices cannot be detected by radio frequency sweeps of the inmate areas (e.g. cells, common areas, etc.).
In the past, attempts at detecting cellular activity within correctional facilities typically consisted of fixed antenna systems, in which, antenna are strategically located throughout the correctional facility and the radio frequency bands used by cellular phones are monitored, reporting detection to a central location. Such systems require an expensive, fixed infrastructure within the correctional facility and only determine that a cellular phone is in use, being incapable of pinpointing the actual user.
Other systems utilize one or more fixed antenna within the facility that terminate the unwanted cellular calls, acting as the cellular phone network, thereby making it difficult or impossible to initiate a call from a cellular phone within the facility. As with the prior attempts, this too does not pinpoint the actual inmate making the call. Furthermore, because signals from this system may extend beyond the prison walls, this system is capable of inadvertently blocking a valid call which could be disastrous if such a call was an emergency call. There are also questions as to whether such a system would be approved for operation by government agencies such as the FCC in the United States. Similarly, jamming devices are available to prevent connections between these cellular phones and the cellular network/towers, but it is also difficult to assure that such jamming devices will not interfere with legitimate calls, especially emergency calls and, again, there are questions related to approval by government agencies.
Another prior attempt to find cellular phones includes portable detection devices that monitor and detect radio frequency emissions in the cellular range. Such devices have been found to be less reliable because, in a prison environment, often there is a tight inmate communication system (e.g. signaling by making certain noises, etc.) that alerts the inmate who is using the cellular phone that a guard is coming in sufficient time as to power down and/or hide the phone before the guard can pinpoint the radio frequency signal. The use of phone (electronics) sniffing dogs faces similar issues when used as the primary means of cell phone detection.
What is needed is a system that will detect and pinpoint radio frequency usage for locating and confiscating of unauthorized communications equipment and report any detected devices.